ProvenanceAnalysis.cpp [plain text]
#include "ObjCARC.h"
#include "ProvenanceAnalysis.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
using namespace llvm;
using namespace llvm::objcarc;
bool ProvenanceAnalysis::relatedSelect(const SelectInst *A,
const Value *B) {
const DataLayout &DL = A->getModule()->getDataLayout();
if (const SelectInst *SB = dyn_cast<SelectInst>(B))
if (A->getCondition() == SB->getCondition())
return related(A->getTrueValue(), SB->getTrueValue(), DL) ||
related(A->getFalseValue(), SB->getFalseValue(), DL);
return related(A->getTrueValue(), B, DL) ||
related(A->getFalseValue(), B, DL);
}
bool ProvenanceAnalysis::relatedPHI(const PHINode *A,
const Value *B) {
const DataLayout &DL = A->getModule()->getDataLayout();
if (const PHINode *PNB = dyn_cast<PHINode>(B))
if (PNB->getParent() == A->getParent()) {
for (unsigned i = 0, e = A->getNumIncomingValues(); i != e; ++i)
if (related(A->getIncomingValue(i),
PNB->getIncomingValueForBlock(A->getIncomingBlock(i)), DL))
return true;
return false;
}
SmallPtrSet<const Value *, 4> UniqueSrc;
for (unsigned i = 0, e = A->getNumIncomingValues(); i != e; ++i) {
const Value *PV1 = A->getIncomingValue(i);
if (UniqueSrc.insert(PV1).second && related(PV1, B, DL))
return true;
}
return false;
}
static bool IsStoredObjCPointer(const Value *P) {
SmallPtrSet<const Value *, 8> Visited;
SmallVector<const Value *, 8> Worklist;
Worklist.push_back(P);
Visited.insert(P);
do {
P = Worklist.pop_back_val();
for (const Use &U : P->uses()) {
const User *Ur = U.getUser();
if (isa<StoreInst>(Ur)) {
if (U.getOperandNo() == 0)
return true;
continue;
}
if (isa<CallInst>(Ur))
continue;
if (isa<PtrToIntInst>(P))
return true;
if (Visited.insert(Ur).second)
Worklist.push_back(Ur);
}
} while (!Worklist.empty());
return false;
}
bool ProvenanceAnalysis::relatedCheck(const Value *A, const Value *B,
const DataLayout &DL) {
A = GetUnderlyingObjCPtr(A, DL);
B = GetUnderlyingObjCPtr(B, DL);
if (A == B)
return true;
switch (AA->alias(A, B)) {
case AliasAnalysis::NoAlias:
return false;
case AliasAnalysis::MustAlias:
case AliasAnalysis::PartialAlias:
return true;
case AliasAnalysis::MayAlias:
break;
}
bool AIsIdentified = IsObjCIdentifiedObject(A);
bool BIsIdentified = IsObjCIdentifiedObject(B);
if (AIsIdentified) {
if (isa<LoadInst>(B))
return IsStoredObjCPointer(A);
if (BIsIdentified) {
if (isa<LoadInst>(A))
return IsStoredObjCPointer(B);
return false;
}
} else if (BIsIdentified) {
if (isa<LoadInst>(A))
return IsStoredObjCPointer(B);
}
if (const PHINode *PN = dyn_cast<PHINode>(A))
return relatedPHI(PN, B);
if (const PHINode *PN = dyn_cast<PHINode>(B))
return relatedPHI(PN, A);
if (const SelectInst *S = dyn_cast<SelectInst>(A))
return relatedSelect(S, B);
if (const SelectInst *S = dyn_cast<SelectInst>(B))
return relatedSelect(S, A);
return true;
}
bool ProvenanceAnalysis::related(const Value *A, const Value *B,
const DataLayout &DL) {
if (A > B) std::swap(A, B);
std::pair<CachedResultsTy::iterator, bool> Pair =
CachedResults.insert(std::make_pair(ValuePairTy(A, B), true));
if (!Pair.second)
return Pair.first->second;
bool Result = relatedCheck(A, B, DL);
CachedResults[ValuePairTy(A, B)] = Result;
return Result;
}